A quick Google shows that this camera is regarded as having a red (saturated) bias.

All digital cameras including my Pentax have a red bias to some extent depending on the strength, quality of the sensor IR filter on the red end of the light spectrum and UV filter on the blue end along with whatever bias the lens coatings offer among various models.

My Pentax K100D has a red bias which usually renders shots of red flowers lit by direct sunlight into flat color red blobs whether I shoot jpeg or Raw.

Have you tried editing the custom DNG profile recipe of your Canon 1D in Adobe DNG Profile Editor? That's the only solution I've found outside of editing the HSL panel in ACR on a shot by shot basis.

While I do not do "color Critical" work, I have long since decided that DPP renders a much superior image as compared to the Adobe products on Canon files. However I have been using the latest version (v7) of Capture One and believe that skin tones and color is better than in DPP and prior versions of Capture One.

With that said I just tried Phocus and pretty impressed with the results. But it certainly does not have the versatility of Capture One.

The problem I have with DPP is its lack of features compared with just about any other raw processor. The most useful thing I find about it is that it gives me something to compare with when I have an image open in ACR or LR - particularly so when it comes to the critical issue of white balance.

I shoot directly to DPP on a laptop when on location. This gives me something to aim at when the files are transferred to the desktop for processing.

I always use Camera Neutral in ACR or LR as my starting point now. A direct comparison with DPP shows that blues are slightly less saturated in ACR/LR. Otherwise, it's a very good match.

As to white balance, more often than not, As Shot and Auto get me a lot closer to what I was seeing in DPP on my (calibrated) laptop than a Custom grey card white balance does. I find Custom is usually far too warm.

The problem I have with DPP is its lack of features compared with just about any other raw processor. The most useful thing I find about it is that it gives me something to compare with when I have an image open in ACR or LR - particularly so when it comes to the critical issue of white balance. ...

That issue has been a constant source of irritation. DPP produces a far more natural color rendition than anything else, even for work that's not color critical, but it has a very limited set of features. It can take loads of time fussing in ACR to get close to the same look. In ACR I often use Camera Faithful or Neutral, but that's just a starting point. as far as I know, Breeze Browser has a much better user interface and uses the same Canon software conversion routines as DPP. I use that in the field but I use ACR for the "real" processing later on. Using ACR I often find it hard to equal the color produced in a couple minutes late at night minutes in a motel room using DPP or Breeze Browser.

In LR 1,2 and 3 it was a 25 pixel sample. In LR 4 it can be expanded up to 289 pixels.I don't know about ACR, but I would think it is very unlikely that it is a single pixel. The chance of error would be very great.

DPP is accurate in colour. It has all the features a raw converter can have; what it lacks has nothing to do with raw conversion but is Photoshop field. ACR/LR do poor with colour for this camera, but you can make it acceptable by editing red primary directly.

Also, am I correct in thinking that LR samples a 25 pixel average (as one sees in the magnifier) whereas ACR is single pixel?

as far as I remember ACR takes into account a variable sized area based on the current magnification of preview (like when you view @ 25% WB tool will use more pixel vs when you view @ 50%) - but the size is not user controllable (what a shame !).